Preparation of alkane phosphonic acids



Patented Sept. 15, 1953 PREPARATION OF ALKANE PHOSPHONIC ACIDS RichardD. Stayner, Albany, \Galif assignor to California Research Corporation,San Francisco, Calif., ,a corporation of Delaware No Drawing. Originalapplication February 4,

1948, Serial No.

6,345. Divided and this application August '28, 1950, Serial 4 Claims.(01. 260-500) 1 "The invention described and claimed in this applicationrelates to a new method of preparing long chain alkane phosphonic acidsin which an alkyl group containing from 0 ;.to 18 carbon atoms isattached to the phosphorus atom by a CETbOIl-tO-{JhOSPhOYHS bond.

This present application is a division of application Serial No. 6,345,filed February 4, 1948, now U. S. Patent 2,587,340, and entitled Estersof Alkane Phosphonic Acids.

Therein hydroxyalkyl and hydroxyalkyl oxyalkylene esters of long chainalkane phosphonic acids are shown to have been prepared by reacting along chain alkane phosphonic acid with an olefin oxide, e. g., ethyleneoxide, propylene oxide or butylene oxide. These esters are characterizedby the presence of oxyalkylene radicals with a hydrogen atom attached tothe terminal oxygen atom.

For purposes of illustration, some of these ester compounds may, forexample, be shown by the following equation:

CH/CH wherein n is an integer of 1 to 10, R is a long chain alkyl ofpreferably 10 to 18 carbon atoms, and R and R represent hydrogen andshort chain alkyl groups.

The reaction of alkylene oxides with alkane phosphonic acids may becarried out at atmospheric pressures, and the reaction temperature maybe varied between the limits of 20-200 C. In the preparation ofpolyglycol esters, a surface catalyst may be used advantageously toincrease the reaction rate, or other catalysts such as sulfuric acid,phosphoric acid, nickel sulfate, boron trifluoride, allryl sulfates,sodium, tertiary amines, etc., may be employed.

I have discovered that the long chain alkane phosphonic acids used forreacting with olefin oxides may be readily prepared from thecorresponding dichlorides by reaction with a carboxylic acid accordingto the equation:

wherein R is an alkyl group of 10 to 18 carbon atoms and R is an alkylgroup such that the re- This process of my invention yieldssubstantially quantitative amounts of the desired long chain alkanephosphonic acid and, furthermore, yields a valuable acid-chlorideby-product in contrast to the prior art by-productof :dilute hydro--.Ch10l'i0.13,0id which results from hydrolysis of alkane phosphonyldichloride with water. 1 :In carrying out this process, I prefer to mixthe ingredients and then heat the mixture for a few minutes at boilingtemperatures, preferably under reflux. In compounding our reactantmixtures at least two moles of the carboxylic acid are used for eachmole of long chain alkane phosphonyl dichloride. After the heatingperiod mentioned above, the acid-chloride is distilled off, followed byany excess carboxylic acid that may be present, preferably using reducedpressure. The above procedure, I have discovered, yields substantiallyquantitative amounts of the desired long chain alkane phosphonic acid ina highly purified condition.

By way of illustrating my inventive process for producing long chainalkane phosphonic acid from long chain alkane phosphonyl dichlorideusing carboxylic acid, the following example is presented:

A mixture of 74.2 parts by weight of octadecane phosphonyl dichlorideand 60 parts of glacial acetic acid was prepared and subsequently heatedto the boiling point. The acetyl chloride formed in the reaction wasthen distilled off from the reaction mass. Next, the residue wassubjected to reduced pressure distillation to remove excess glacialacetic acid. The final product consisted of 6'7 parts by weight and wasidentified as octadecane phosphonic acid (CisHsoPOs) by the followinganalysis:

Per cent Phosphorus found 9.1 Phosphorus calculated 9.3

Chlorine found Trace The presence of but a trace of chlorine indicatedthat the final product was substantially pure, long chain alkanephosphonic acid.

The above description is intended to be illustrative only, and anymodification which conforms with the spirit of the invention isunderstood to be included within the scope of the following claims.

I claim:

1. The method of preparing a long-chain alkane phosphonic acid havingfrom 10 to 18 carbon atoms in the alkyl group attached to the phosphorusatom, said method comprising heating to its boiling point asubstantially anhydrous mixture of 1 mole of a long-chain alkanephosphonyl dichloride having from 10 to 18 carbon atoms in the alkylgroup attached to the phosphorus atom, and at least 2 moles of a low mo-,lecular weight saturated aliphatic monocarboxylic acid, the acidchloride of which boils at a temperature below the boiling point of saidlongchain alkane phosphonyl dichloride.

2. The method of preparing a long-chain alkane phosphonic acid havingfrom 10 to 18 carbon atoms in the alkyl group attached to the phosphorusatom, which comprises forming a substantially anhydrous mixture of 1mole of long-chain alkane phosphony1 dichloride having from 10 to 18carbon atoms in the alkyl group attached to the phosphorus atom, and atleast 2 moles of a low molecular weight carboxylic acid having theformula RCOOI-I, wherein Ris an alkyl radical containing from 1 to 4carbon atoms,

the acid chloride of which boils at a temperature below the boilingpoint of said long-chain alkane phosphonyl dichloride; and heating saidmixture to its boiling point to yield said longchain alkane phosphonicacid and a chloride of said carboxylic acid boiling below the boilingpoint of said alkane phosphonyl dichloride.

3. The method of preparing long-chain alkane phosphonic acids havingfrom 10 to 18 carbon atoms in the alkane portion thereof, whichcomprises mixing one mole of long-chain alkane phosphonyl dichloridewherein the alkyl group contains from 10 to 18 carbon atoms with atleast two moles of glacial acetic acid; and heating the resultingsubstantially anhydrous mixture to its boiling point.

4. The method of preparing long-chain alkane phosphonic acids havingfrom 10 to 18 carbon atoms in the alkane portion, which comprises mixingone mole of long-chain alkane phosphonyl dichloride wherein the alkylgroup contains from 10 to 18 carbon atoms with at least two moles ofnon-aqueous propionic acid; and heating the resulting mixture to itsboiling point,

RICHARD D. STAYNER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,304,157 Engelm-an et al. Dec. 8, 1942 2,492,994 Harman etal. Jan. 3, 1950 OTHER REFERENCES Kosolapofl, J. Am. Chem. Soc., vol.67, pp. 1180-2 (1945).

Kosolapofi, Organophosphorus Compounds, pp. '70-'71 (1950).

1. THE METHOD OF PREPARING A LONG-CHAIN ALKANE PHOSPHONIC ACID HAVINGFROM 10 TO 18 CARBON ATOMS IN THE ALKYL GROUP ATTACHED TO THE PHOSPHORUSATOM, SAID METHOD COMPRISING HEATING TO ITS BOILING POINT ASUBSTANTIALLY ANHYDROUS MIXTURE OF 1 MOLE OF A LONG-CHAIN ALKANEPHOSPHONYL DICHLORIDE HAVING FROM 10 TO 18 CARBON ATOMS IN THE ALKYLGROUP ATTACHED TO THE PHOSPHORUS ATOM, AND AT LEAST 2 MOLES OF A LOWMOLECULAR WEIGHT SATURATED ALIPHATIC MONOCARBOXYLIC ACID, THE ACIDCHLORIDE OF WHICH BOILS AT A TEMPERATURE BELOW THE BOILING POINT OF SAIDLONGCHAIN ALKANE PHOSPHONYL DICHLORIDE.